Mendelian Inheritance - Mendel's Laws of Heredity

From his monohybrid cross results, Mendel proposed two rules, today called his laws of inheritance. The Law of Dominance states that characters are controlled by discrete factors that occur in pairs, and that when a pair of factors differs, one member (the dominant allele) is expressed and the other (the recessive allele) is masked; this single rule explains both why only one parental character appears in the F1 generation of a monohybrid cross and why both characters reappear in the F2 generation in a 3:1 ratio. The Law of Segregation (also called the Law of Purity of Gametes) states that the two alleles of a pair never blend together - both original characters remain intact and can still be seen in the F2 generation even though one of them was completely hidden in F1. During gamete formation, the two alleles of a pair separate (segregate) from each other, so that every gamete carries only one of the two alleles; a homozygous parent therefore produces only one kind of gamete, while a heteroz …